This invention relates to a gravity actuated protective cover assembly employed to expose or close the open end of an upright exhaust pipe of an internal combustion engine and more particularly, to an improved cover assembly having novel means for absorbing energy shock at opening and closing of the cover on the stack.
The herein invention achieves important advantages over the cover devices described in U.S. Pat. Nos. 2,983,216, 4,059,045, and 4,255,928. A protective cover assembly of the type described in said patents normally is mounted on the exhaust stack of the engine proximate the open upper end of the stack. The cover member is pivotally mounted on the assembly for movement from a normal position overlying said open end so as to close the same to a second position exposing said open end. In the normal closed position of the cover member, rain, snow or other debris is prevented from entering the stack. During operation of the engine, exhaust gases rise in the stack to impinge against the cover member with sufficient force to pivot the cover member fully to an open position and permit discharge of the exhaust gases through the opened end of the stack. Past experience with such cover movement has been occasioning of considerable shock at the fully open and closed positions of the cover member by reason of the pivotal movement of a weighted cover member such as commonly used in such assemblies. During alternate high speed and low speed operation of the engine such a weighted cover member is pivoted successively between open and closed positions thereof with accompanying substantial impact shocks. Even at idle speed of the engine, the cover will flutter between closed and slightly open positions with accompanying impact shocks.
In the prior art patents, the cover assemblies have been constructed using a clamp formed of two metal straps which are welded together face to face for a short portion of their combined length. At a second portion of their combined length, the straps form a loop sized to encircle the exhaust stack. A plastic bumper member is mounted upon the welded portion of the straps in position to absorb impact shock and reduce the noise as the pivotal cover pivots to said open and closed positions on the end of the stack. In some cases, after extended use the repeated shock of impacts at the open and closed positions of the cover has generated very strong vibrations which can rupture the welded junction, particularly with larger covers employed in heavy duty vehicles.
The improved cover assembly of this invention eliminates welding of the support straps to each other and thereby prevents breakage of the cover assembly due to such sustained impact shock of the cover member for extended periods of use.